As I said earlier, there shouldn't be an arbitrary line between the
installer and the packages. People aren't installing "Etch the
installer" or "Etch the packages", they're installing "Etch the
release". Test both parts simultaneously, as a single unit, because
that's how your users are going to use them.

Mat has an important point here. Too often, I've seen: "I'm sorry
about the bugs you've encountered post-install. It sounds like the
install itself went fine. I'm closing this report." Usually, the
person making the report doesn't have a clue about the fine points of
which package team is responsible for the bug she has encountered.
The person best able to make that determination is the person who
fields the installation report. But it seems that person can't be
bothered to pass the report along, and feels no responsibility to try.